matplotlib: fix build

Author: T-Dynamos

pythonforandroid/recipes/matplotlib/__init__.py

@@ -78,6 +78,7 @@ def get_recipe_env(self, arch, **kwargs):
         free_lib_dir = join(freetype.get_build_dir(arch.arch), 'objs', '.libs')
         free_inc_dir = join(freetype.get_build_dir(arch.arch), 'include')
         env['CFLAGS'] += f' -I{free_inc_dir}'
+        env['CXXFLAGS'] += f' -I{free_inc_dir}'
         env['LDFLAGS'] += f' -L{free_lib_dir}'
 
         # `freetype` could be built with `harfbuzz` support,